Reproduction

The group is responsible for the development and application of most artificial breeding techniques currently employed in the Australian sheep industry. Technology transfer is continuing through undergraduate/postgraduate teaching and industry training. Research areas include the application of semen analysis by computerised image analysis, utilisation of chilled semen, development of transcervical insemination techniques, application of sexed semen in artificial insemination, techniques for collection of oocytes from juvenile animals for in vitro embryo production and preservation of embryos by vitrification. Developments have been mainly applied in sheep but also in goats.

Research includes the development in sheep and pigs of techniques for in vitro maturation and fertilisation (IVM/IVF) of oocytes, fertilisation of in vitro matured oocytes by intracytoplasmic sperm injection (ICSI), in vitro culture of pre-implantation embryos and production of offspring from juvenile animals. These studies are fundamental in nature and examine not only requirements for maturation and fertilisation of oocytes and viable growth of embryos, but also the basis of sperm capacitation and the time-course of fertilisation events under in vitro conditions.

Sex preselection in sheep, pigs, horses and primates by separation of X and Y chromosome bearing spermatozoa
The ability to preselect the sex of offspring of agriculturally important animals would have significant benefits to the livestock industries. Research aims at the production of sexed offspring using DNA-based cell sorting by flow cytometry, through in vitro embryo production by IVF or ICSI and artificial insemination.
There is also work under way on the use of fluorescence-activated cell sorting technology for the prediction of viability and fertilising capacity of flow sorted (for sex) mammalian spermatozoa and on the improvement of sperm viability after sorting. Boar, bull and ram spermatozoa have been used as models and work is also undertaken on horses and on primates aimed at improved conservation of endangered species.

The hypothesis is based on changes at the molecular level in membrane stability and flagella movement, rather than gross membrane damage, as a result of freezing and thawing, which renders spermatozoa functionally capacitated. Techniques utilised include computer assisted sperm movement analysis and fluorescence and flow-cytometric membrane analysis. The influence of membrane and flagella status on fertilising capacity is tested in vitro and in field artificial insemination trials.